On 24.07.2024 17:31, Oleksii Kurochko wrote:
> The patch introduces stuff needed to decode a reason of an
> exception.
>
> Signed-off-by: Oleksii Kurochko <oleksii.kuroc...@gmail.com>
> Acked-by: Alistair Francis <alistair.fran...@wdc.com>
> Acked-by: Jan Beulich <jbeul...@suse.com>
> ---
> Changes in V11:
> - Nothing changed. Only rebase.
> ---
> Changes in V10:
> - add Acked-by: Jan Beulich <jbeul...@suse.com>
> ---
> Changes in V9:
> - This patch was reverted as breaks both release and randconfig builds.
> I don't see the failures now. ( probably it was because of printk usage
> which was not ready at that moment ).
> - drop inclusion of <asm/csr.h> and <asm/early_printk.h>
> - add <asm/riscv_encoding.h> for CAUSE_* in decode_trap_cause().
> ---
> Changes in V8:
> - fix typo in return string from decode_reserved_interrupt_cause
> - add Acked-by: Alistair Francis <alistair.fran...@wdc.com>
> ---
> Changes in V7:
> - Nothing changed. Only rebase.
> ---
> Changes in V6:
> - Remove usage of LINK_TO_LOAD() due to the MMU being enabled first.
> - Change early_printk() to printk()
> ---
> Changes in V5:
> - Remove <xen/error.h> from riscv/traps/c as nothing would require
> inclusion.
> - decode_reserved_interrupt_cause(), decode_interrupt_cause(),
> decode_cause, do_unexpected_trap()
> were made as static they are expected to be used only in traps.c
> - use LINK_TO_LOAD() for addresses which can be linker time relative.
> ---
> Changes in V4:
> - fix string in decode_reserved_interrupt_cause()
> ---
> Changes in V3:
> - Nothing changed
> ---
> Changes in V2:
> - Make decode_trap_cause() more optimization friendly.
> - Merge the pathc which introduces do_unexpected_trap() to the current one.
> ---
> xen/arch/riscv/traps.c | 80 +++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 79 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/riscv/traps.c b/xen/arch/riscv/traps.c
> index 5415cf8d90..37cec40dfa 100644
> --- a/xen/arch/riscv/traps.c
> +++ b/xen/arch/riscv/traps.c
> @@ -9,13 +9,91 @@
> #include <xen/sched.h>
>
> #include <asm/processor.h>
> +#include <asm/riscv_encoding.h>
> #include <asm/traps.h>
>
> -void do_trap(struct cpu_user_regs *cpu_regs)
> +static const char *decode_trap_cause(unsigned long cause)
> +{
> + static const char *const trap_causes[] = {
> + [CAUSE_MISALIGNED_FETCH] = "Instruction Address Misaligned",
> + [CAUSE_FETCH_ACCESS] = "Instruction Access Fault",
> + [CAUSE_ILLEGAL_INSTRUCTION] = "Illegal Instruction",
> + [CAUSE_BREAKPOINT] = "Breakpoint",
> + [CAUSE_MISALIGNED_LOAD] = "Load Address Misaligned",
> + [CAUSE_LOAD_ACCESS] = "Load Access Fault",
> + [CAUSE_MISALIGNED_STORE] = "Store/AMO Address Misaligned",
> + [CAUSE_STORE_ACCESS] = "Store/AMO Access Fault",
> + [CAUSE_USER_ECALL] = "Environment Call from U-Mode",
> + [CAUSE_SUPERVISOR_ECALL] = "Environment Call from S-Mode",
> + [CAUSE_MACHINE_ECALL] = "Environment Call from M-Mode",
> + [CAUSE_FETCH_PAGE_FAULT] = "Instruction Page Fault",
> + [CAUSE_LOAD_PAGE_FAULT] = "Load Page Fault",
> + [CAUSE_STORE_PAGE_FAULT] = "Store/AMO Page Fault",
> + [CAUSE_FETCH_GUEST_PAGE_FAULT] = "Instruction Guest Page Fault",
> + [CAUSE_LOAD_GUEST_PAGE_FAULT] = "Load Guest Page Fault",
> + [CAUSE_VIRTUAL_INST_FAULT] = "Virtualized Instruction Fault",
> + [CAUSE_STORE_GUEST_PAGE_FAULT] = "Guest Store/AMO Page Fault",
> + };
> +
> + if ( cause < ARRAY_SIZE(trap_causes) && trap_causes[cause] )
> + return trap_causes[cause];
> + return "UNKNOWN";
> +}
While I committed this as-is, two more points: First, as soon any any
such array access becomes potentially reachable because of guest
activity, it wants to use array_access_nospec() or alike. Second, and
somewhat related, it may be desirable to avoid such double accesses.
Hopefully the compiler will do that for you. But
const char *res = cause < ARRAY_SIZE(trap_causes) ? trap_causes[cause]
: NULL;
return res ?: "UNKNOWN";
might be worthwhile anyway.
Jan
